Differences in the Microstructures and Tensile Properties of Each Zone of Inertia Friction Welded Joints of TA19 Titanium Alloy
Round 1
Reviewer 1 Report
The manuscript is devoted to the study of the effect of inertial friction welding (IFS) on the microstructure and mechanical properties of the TA19 titanium alloy. The authors carried out a thorough analysis of all zones of the welded zones and made significant conclusions about the effect of the process on the microstructure and mechanical properties. The manuscript is well structured and undoubtedly of scientific interest to researchers in the field of titanium alloys.
I have a few small comments on the manuscript:
1. Tensile properties. Values of the tensile properties of the 119.14 GPa and 972.64 MPa were too high precision. What is the standard deviation of the obtained values? Authors should specify a confidence interval and adjust the values of mechanical property values according to the confidence interval.
2. Figure 6. It will be better to correct the graphs - it is necessary to start the values of the axes from 0 values.
3. Figure 6b. Authors should change the plot legend from dots to lines.
Author Response
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Reviewer 2 Report
The paper "Microstructure and Tensile Properties of Inertia Friction Welded 2 Joints of TA19 Titanium Alloy" in general contains interesting results and is of scientific value. However, English is poor here. It is very difficult to read the text and perceive any information. There are incomprehensible wordings that are difficult for the perception of the sentence (on 4 lines). The layout of the article is rather sloppy, there are dots where apparently they should not be, in many places there are no spaces, etc. All this greatly complicates the review process and does not allow to fully appreciate the merits of the paper. In my opinion, a thorough revision of the text and then re-review is required. One more global issue concerns the focus of work. In its structure and many results, the paper is very similar to the previously published one https://doi.org/10.1186/s10033-020-00507-6. In the introduction, the authors note that the main difference of this work is that it will carry out a fractographic analysis of various zones of IFW. This has indeed been done, however, in other respects, some of the results duplicate those described earlier. In this regard, it seems to me appropriate to change the title of the article and shift the focus to what was received for the first time.
Author Response
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Reviewer 3 Report
This research article mainly focuses on the microstructure and tensile properties of inertia friction welded joints of TA19 titanium alloy, verifying microstructure, alloying elements, tensile properties and fracture behavior as the welded specimen zones change.
Although this paper could be interesting to the readers of the journal and have applications in both industry and aerospace, there is a need for a careful review by the authors, who need to better clarify the novelty of the research project with respect to the state of the art, take better care of the syntax, better explain the process window, compare the results with the literature, and clarify whether and how many experimental replications have been completed.
Below are all the main points to which the authors should reply:
1. The abstract is certainly clear but there is no reference to the most important numerical results of the paper. Therefore, a numerical discussion of the expressed concepts is also needed.
2. The introduction should better clarify the research project presented, i.e., the advances, the novelties of the proposed paper, compared to the state of the art.
3. The level of English, although correct in grammar, and spelling, is still too low in relation to syntax and the presence of many repetitions. It should definitely be better taken care of.
4. In many cases, such as in line 28, too many citations were merged together, thus not defining the contribution of each one with regard to the concepts expressed in the paper. In my opinion, a maximum of 2 citations should be merged together. Thus, multiple citations should be divided and the contribution of each one within the paper should be better brought out.
5. Still referring to the introduction, the study of the state of the art regarding IFW processes and the study of mechanical properties of welded joints is definitely lacking, limited to lines 54-57. Has no other author studied the subject of IFW? With which results?
6. The choice of experimental parameters of the IFW process was neither motivated nor supported by references. The choice of parameters, such as speed, pressure, etc., is certainly motivated. It should be reported.
7. Regarding the chemical etching reported in lines 89-90, for how long and at what temperature did it occur?
8. About lines 92-94, the choice to apply circular grooves should be better justified in the text. Why reduce the section in 3 parts, compared to the original specimen? Which information can the tensile test with or without grooves bring?
9. About lines 99-100, if the authors know the magnifications of the OM and SEM micrographs, I suggest to report them in the paper.
10. About Figure 6a, at line 252, it is not specified to which specimens the different colors correspond.
11. It is not made clear in the paper whether or not there are experimental replicates of the different specimens or tests. This denotes a difficulty in understanding the replicability of the tests conducted.
12. The comparison of the experimental results with the literature is quite limited. It denotes a low scientific soundness of the paper and a poor referability of the results to the literature. Therefore, this point should definitely be better taken care of.
13. The conclusions are certainly valid, as they correctly refer to the most important numerical results of the work. However, future developments of the work and the contribution of the obtained results to the scientific community are not highlighted.
14. Linked to the previous point, the references are few. By expanding the state of the art, this section will also benefit from it.
Author Response
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Author Response File: Author Response.docx
Round 2
Reviewer 2 Report
The authors did notable work to improve the article, taking into account the comments of the reviewers. In its current form, the paper looks much better. However, there are still issues that need to be revised:
1) Table 2. In some cases, the sum of the content of elements in % is 100, in some it is not (for example, spot 2). Why? Maybe some other elements are not shown here, the composition of which can be affected by welding (for example, O)? Moreover, there are strange results of recalculation between atomic and weight percepts. What atomic mass were used for the recalculation?
2) Line 17-19: “In tensile tests, specially designed tensile specimens with circular grooves were used to test the tensile properties of different zones of the IFW joint. After tensile tests, the stress–strain curve and tensile fracture were analyzed; the results showed that the tensile strength of the welded joint increased, but the plasticity decreased from BM to WZ.” These two sentences repeat word ‘tensile’ six times. It seems too much, please rework these sentences.
3) Line 184, 185: “As shown in Figure 4(d), the temperature of the welding interface increased to 1200 ℃ [17,19], which is higher than the TA19 β phase-transition temperature (950±20℃) and there was significant plastic deformation.” It is not shown directly in the Figure 4d that temperature of welding interface increased to 1200 ℃. This conclusion can be done based on the structure analysis. Please rephrase.
4) Line 203-207: “Elemental analysis of the equiaxed α-phase and β-basic-phase was performed for the HAZ; the results showed that the content of Mo, the eutectic β-phase stabilizing element of the titanium alloy in the isometric α-phase, was zero, whereas the content of Mo elements in the β-basic phase exceeded the Al elements, sharply increasing to 10.9%, which indicated that Mo elements in the HAZ still played a role in retaining the large β-phase at room temperature.” Unclear sentence very difficult for understanding with unclear wording. Please rephrase it.
5) Why different formulations (β-basic phase and β-phase) is used? What is the difference?
Author Response
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Author Response File: Author Response.docx
Reviewer 3 Report
The authors in the 2nd version of their paper have completed consistent improvements to both the introduction, better clarify the novelty and the targets of the research project, and the materials and methods section, better detailing the experimental choices and methods, the process window and the number of replications of each test. The English language and syntax have been also improved, as required to an international journal paper.
Despite this, there are several points that the authors have not developed with proper attention or have just ignored, which concern the conclusions, the study of the state of the art and the reference of the results to the literature, and which denote a low scientific soundness of the paper.
Below are detailed all the remaining points to which the authors should carefully reply:
5. Still referring to the introduction, the study of the state of the art regarding IFW processes and the study of mechanical properties of welded joints is definitely lacking, limited to lines 54-57. Has no other author studied the subject of IFW? With which results?
A: We have given some descriptions of titanium IFW joints, which you may not have noticed due to the short description. Meanwhile, we have made the following modifications. The following text is lines 55 to 60 of the present manuscript.
R: The introduction continues to be lacking with regard to comparison with the scientific literature. Searching in Google Scholar for example, in 1-2 minutes, I found many papers pertaining to the topic, including the following:
- https://doi.org/10.1533/9780857095169.1.25
- https://doi.org/10.1016/j.jmapro.2016.09.008
- https://doi.org/10.3390/pr10122548
- https://doi.org/10.1515/ijmr-2020-7770
Therefore, I expect more effort from the authors in curating the state of the art, which is still lacking regarding the studies and results already achieved in the literature, in relation to the IFW process of titanium alloys.
12. The comparison of the experimental results with the literature is quite limited. It denotes a low scientific soundness of the paper and a poor referability of the results to the literature. Therefore, this point should definitely be better taken care of.
A: Thanks for the reviewer's constructive suggestions, but there are few references on the inertial friction welding of titanium alloy. Our team has done some studies on the inertial friction welding of TA19 titanium alloy (reference 16,17), so we chose to reference and compare with some reliable information we have obtained.
R: Based on a more extensive and detailed study of the state of the art, the referability of results to the literature should be certainly improved.
13. The conclusions are certainly valid, as they correctly refer to the most important numerical results of the work. However, future developments of the work and the contribution of the obtained results to the scientific community are not highlighted.
A: As for the highlights of our research, as shown in Answer 2, we have made a number of changes in the introduction to highlight the innovation and contribution of our research.
R: Point not implemented by the authors.
14. Linked to the previous point, the references are few. By expanding the state of the art, this section will also benefit from it.
A: There are few references on IFW of titanium alloys. Out of rigor, we chose the reliable data our team had obtained for comparison, hoping that the reviewer could take our ideas into comprehensive consideration.
R: Point not implemented by the authors. Linked to point 5 above, obviously.
Author Response
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Author Response File: Author Response.docx
Round 3
Reviewer 3 Report
The authors in the 3rd version of their paper have completed improvements, though not extensive, but still sufficient, to the abstract, the introduction and the experimental results section, taking better care, as requested, of the study of the state of the art and the reference of the results to the literature, in order to raise the scientific soundness of the paper, which was previously insufficient.
At the same time, however, despite the two previous rounds of revisions, there are still aspects that continue to be carelessly or ignored by the authors, in relation to the future developments of the paper and especially to the contribution of the main results to the scientific community.
So, below are detailed the two remaining points to which the authors should carefully reply:
5. Still referring to the introduction, the study of the state of the art regarding IFW processes and the study of mechanical properties of welded joints is definitely lacking, limited to lines 54-57. Has no other author studied the subject of IFW? With which results?
A: We have given some descriptions of titanium IFW joints, which you may not have noticed due to the short description. Meanwhile, we have made the following modifications. The following text is lines 55 to 60 of the present manuscript.
R: The introduction continues to be lacking with regard to comparison with the scientific literature. Searching in Google Scholar for example, in 1-2 minutes, I found many papers pertaining to the topic, including the following:
- https://doi.org/10.1533/9780857095169.1.25
- https://doi.org/10.1016/j.jmapro.2016.09.008
- https://doi.org/10.3390/pr10122548
- https://doi.org/10.1515/ijmr-2020-7770
Therefore, I expect more effort from the authors in curating the state of the art, which is still lacking regarding the studies and results already achieved in the literature, in relation to the IFW process of titanium alloys.
A2: We added the following text in lines 56 to 66, and lines 74 to 77 to fully introduce other scholars' researches on IFW joints and to compare with our results.
R2: All the lines indicated in the responses to the reviewer were never the ones actually changed in the text. I also point out to the authors to better check lines 83-84, because the phrase "the fracture form from ductile fracture" seems to me to be an obvious and incorrect repetition in the text of the following line. Same thing applies to line 285.
13. The conclusions are certainly valid, as they correctly refer to the most important numerical results of the work. However, future developments of the work and the contribution of the obtained results to the scientific community are not highlighted.
A: As for the highlights of our research, as shown in Answer 2, we have made a number of changes in the introduction to highlight the innovation and contribution of our research.
R: Point not implemented by the authors.
A2: We added the following text in lines 330 to 338 to highlight the future development of our research and the contribution of the results obtained to the scientific community.
R2: Point not implemented by the authors. Nothing has in fact changed on the conclusions. In addition, the lines indicated by the authors, which are actually 364-371, report a simple comparison of their results with those of another paper [21], as was required in 12th item of Round II review. Nothing, however, is present regarding the future development of research and the contribution of the results obtained to the scientific community.
Author Response
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